Therapeutic antibodies with reduced levels of fucosylation or absent fucosylation have been shown to exhibit enhanced antibody-dependent cellular cytotoxicity (ADCC) due to increased binding to FcγR III. Increased ADCC has been associated with improved in vivo efficacy in animal models and in the clinic. Other therapeutic antibodies dependent on ADCC for efficacy are also expected to benefit from reduced levels of fucosylation or absent fucosylation. In addition, fucosylation levels of antibodies are an important product attribute that is desirable to match during the production of bio similar products.
Antibody fucosylation may be reduced by use of cell lines in which one or more of the key enzymes involved in protein fucosylation (GDP-mannose dehydratase (GMD), GDP-fucose synthase (GFS), or alpha-(1,6)-fucosytransferase 8 (FUT8) are either genetically knocked out or through chemical inhibition or inactivation of these enzymes. The use of knockout cell lines often requires optimization of manufacturing processes in these cell lines. Even so, cell growth characteristics, product yields, and product attribute qualities may be sub-optimal. In contrast, a small molecule inhibitor or inactivator of enzymes involved in fucosylation may be used to reduce antibody fucosylation without resort to use of engineered cell lines. The alpha-mannosidase inhibitor kifunsenine reduces antibody fucosylation in cell culture but increases high mannose glycan structures resulting in faster clearance of the antibody.
Described herein are novel small molecules designed to reduce antibody fucosylation efficiently without undesirable effects on cell growth or viability, modification of high mannose structures, or, in some cases, being incorporated into antibody glycans.